US3911240A

US3911240A - Dual spring load break switch

Info

Publication number: US3911240A
Application number: US434478A
Authority: US
Inventors: Louis S Henderson; Gustav E Lachman
Original assignee: Pringle Electrical Manufacturing Co
Current assignee: Pringle Electrical Manufacturing Co
Priority date: 1974-01-18
Filing date: 1974-01-18
Publication date: 1975-10-07
Anticipated expiration: 1992-10-07

Abstract

A load break switch having two independent energy-storing spring drives, one for opening the switch, and one for closing the switch, is disclosed. Movement of a loading arm in one direction drives an opening cam to load one spring drive for opening the switch. Movement of the loading arm in a second direction drives a closing cam that loads a second spring drive which closes the open switch. A linear induction motor or hand lever drives the loading arm. A solenoid-operated or manually operated trigger controls unlatching of the switch opening drive. The solenoid is controlled by a circuit for detecting the occurrence of hazardous electrical conditions.

Description

United States Patent Henderson et al.

Oct. 7, 1975 DUAL SPRING LOAD BREAK SWITCH [75] Inventors: Louis S. Henderson, Lafayette Hill;

Gustav E. Lachman, Levittown, both of Pa.

[73] Assignee: Pringle Electrical Manufacturing Company, Fort Washington, Pa.

[22] Filed: Jan. 18, 1974 [21] Appl. No.: 434,478

[52] US. Cl. 200/153 SC; 335/76 [51] Int. Cl. HOIH 3/30 [58] Field of Search 200/153 SC, 154, 67 A, 200/67 B; 335/76, 190, 193, 171

[56] References Cited UNlTED STATES PATENTS 3,551,627 12/1970 Bordak 200/153 SC 3,772,489 11/1973 Wilson 200/153 SC X 3,811,022 5/1974 Guidosh 200/153 SC X Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. Smith Attorney, Agent, or F irm-Synnestvedt & Lechner 5 7] ABSTRACT A load break switch having two independent energystoring spring drives, one for opening the switch, and one for closing the switch, is disclosed. Movement of a loading arm in one direction drives an opening cam to load one spring drive for opening the switch. Movement of the loading arm in a second direction drives a closing cam that loads a second spring drive which closes the open switch. A linear induction motor or hand lever drives the loading arm. A solenoidoperated or manually operated trigger controls unlatching of the switch opening drive. The solenoid is controlled by a circuit for detecting the occurrence of hazardous electrical conditions.

13 Claims, 12 Drawing Figures H -ufu e e U.S. Patent 0a. 7,1975

Sheet 2 of 8 U.S. Patent Oct. 7,1975

Far

US. Patent Oct. 7,1975 Sheet 3 of8 3,911,240

US. Patent Oct. 7,1975 Sheet 4 of 8 3,911,240

US. Patent Oct. 7,1975 Sheet 5 of8 3,911,240

Sheet 6 of 8 US. Patent Oct. 7,1975

US. Patent Oct. 7,-1975 Sheet 7 of8 3,911,240

US. Patent Oct. 7,1975 Sheet 8 of 8 3,911,240

WTNTMHJP i Lk DUAL SPRING LOAD BREAK SWITClI-I BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to load break switches, and particularly to load break switches which are adapted to be opened by an actuating mechanism in response to the detection of various hazardous electrical conditions.

2. Description of the Environment of the Invention and the Prior Art Load break switches are frequently used as service entrance equipment for facilities housing operations having high electrical energy requirements. These switches are placed across incoming power lines to control the supply of electrical power to a building, to various parts of the building, or to particular equipment. Typically, the switches are used in applications having load currents on the order of 4006000 amperes. Because of the high service loads which must be carried by these switches, it is necessary to construct components of the switch, such as the switch blades, from relatively large, heavy parts. Also, to minimize the resistance between the blades and fixed contacts of the switch, these parts are usually engaged under high pressures, such as are developed in the bolted contact type of switch which is commonly used in these applications. Because the switch blades are heavy and are held in engagement with the stationary contacts under high pressure, and because most switches have several blades sets, usually three or more with generally two or four blades per set, the mechanical forces necessary to open and close the switches are substantial.

Load break switches are equipped with actuating systems which are responsive to the detection of various undesirable'events, such as the occurrence of a ground fault, phase loss, or blown fuses, etc., so that the incoming power can be cut off by the switch when one of these conditions occurs. Because of the high load cur rents that are carried by these switches, the contacts must open and close rapidly to minimize arcing and thereby avoid pitting and deterioration of the switch contacts. Because the movable switch blades are rela tively heavy, it is necessary to employ powerful actuating mechanisms to open these switches quickly. Also, the actuating mechanisms must have a very high degree of reliability because of the extensive damage which can result if the switch fails to operate. In this regard, it should be noted that these switches, in normal cir cumstances, are called upon to operate very infrequently, so that a switch may remain closed for several years at a time. It is therefore important that the actuating mechanism be capable of withstanding the effects of prolonged inactivity.

It should also be realized that the actuating mechanism for the switch must be capable of opening the switch even under conditions of significantly reduced voltage, for example, as sometimes occurs when there is a ground fault. Standards set by testing laboratories for this equipment require that the actuating mechanism be capable of opening the switch under conditions in which only 55% of normal voltage is available. Thus, actuating mechanisms utilizing electric motors to open the switch are undesirable, as these motors will barely operate under such reduced voltage conditions. For this reason, designs utilizing springs or similar energystoring devices, for storing sufficient power to open the switch, have been proposed. While in some designs, a manually actuable lever is provided for loading the energy-storing springs in the actuating mechanism, for larger switches, the amount of force required to compress the springs is great, and it has become necessary to employ rotary motors with gear reducers to load the actuating system. A result of the use of such drive systems has been that the ease of emergency manual operation of the switch is reduced, because the drive system must somehow be disengaged before manual operation can be accomplished.

In addition, such load break switches may be placed where access is difficult and actuation from a position remote from the switch is desirable. Further, in some designs employing manually rotated levers for energizing an actuating spring, the operation of the actuating mechanism to open the switch also causes the hand lever to be swung rather sharply with the full impetus of the spring behind it. This can result in serious physical injury to persons who are close to the switch when it is opened by the detection of a fault.

SUMMARY OF THE INVENTION According to the invention herein disclosed, the actuating mechanism of a load break switch includes at least two energy-storing elements operating through cams to open and close the switch. One of the energystoring elements is loaded and held in compressed condition to supply energy for opening the switch. The other energy-storing element is loaded and then allowed to release its energy during the actuation cycle to close the switch. The force necessary to load the energy-storing members may be derived from a linear induction motor. When the motor moves in one direction, one of the energy-storing members is loaded. When the motor moves in an opposite direction to return to its starting position, the other energy-storing member is loaded. Alternately, the force necessary to load the energy-storing members may be derived from a hand lever. The switch is opened either manually or electrically by a trip system, which releases a cam to allow the energy-storing member to open the switch through an appropriate linkage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation view of a three-pole load break switch, employing an actuating mechanism in accordance with the invention herein disclosed, the switch being in closed position.

FIG. 2 is an end view of the switch shown in FIG. 1.

FIG. 3 is a front elevational view of a preferred form of switch actuating mechanism showing the position of various parts when the switch is open.

FIG. 4 is a plan view of the switch actuating mechanism shown in FIG. 3.

FIG. 5 is an enlarged front elevational view of the switch actuating mechanism showing the position of the parts when the mechanism has undergone a first part of its cycle.

FIG. 6 is an enlarged front elevational view of the actuating mechanism showing the position of some of the parts just prior to completion of a full cycle.

FIG. 7 is a front elevational view of the switch actuating mechanism showing the position of the parts at completion of the cycle, the switch having been closed.

FIG. 7A is a fragmentary view showing the position of certain parts shown in FIG. 7 in another operating position.

FIG. 8 is a fragmentary view of the spring loader and associated parts, the view being taken along line 8-8 of FIG. 9.

FIG. 9 is a partial plan view of some of the cam and latching structure.

FIG. 10 is a sectional view of the operating lever and associate parts taken along line 1010 of FIG. 7.

FIG. 11 is a schematic drawing of the control and drive circuitry for the induction motors.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, there is shown a preferred embodiment of load break switch comprising a frame F and a switch assembly SW mounted on the frame. The switch SW is shown a three-pole switch comprised of blades 33 pivotted at points 34 and movable in an are into and out of engagement with stationary tongues 35. The blades 33 are fixed to an electrically non-conductive crossbar 31 so that the blades 33 move conjointly. For purposes of the invention, the switch SW can be any movable blade type switch; however, it is preferred that the switch SW be of the bolted contact type to ensure positive engagement of the switch blades 33 with the tongues 35.

Also mounted on the frame F is a switch-actuating mechanism A for opening and closing the switch SW.

The actuating mechanism includes an operating lever 24, which is rotatably mounted on operating shaft 41 to swing in an are between a position adjacent the switch SW as shown in FIG. 1, and a position spaced away from the switch SW as shown in FIG. 3. The operating lever 24 carries at an outer end thereof a pin 24a. The pin 24a is linked to the crossbar 31 by a suitable universal-type swivel coupling 32. Thus it can be seen that the operating lever 24, when it is positioned as shown in FIG. 1, causes the switch SW to be closed so that the switch blades 33 are engaged with the fixed tonges 35, as shown in FIG. 2. When the operating lever 24 is pivoted to its second position, the blades 33 move arcuately out of engagement with the fixed tongues 35. The manner in which the operating lever 24 is caused to move by the actuating mechanism A will be hereinafter described in more detail.

Suitable connections (not shown) are provided to connect power lines to the fixed tongues 35 and the pivoted blades 33 via the opposing fixed hinge tongues 35a.

Also mounted on the frame F is a drive system D for loading the actuating mechanism A. In the preferred embodiment herein described, the drive system D includes a pair of

linear induction motors

20,20, each comprised of a core rod 28 mounted between the sides of and extending across the frame F. Coil-carrying

members

26,26 surround each of the

core rods

28,28, and are movable therealong. The

members

26,26 are interconnected at their ends by end plates 25,2511. The end plates ride on guide bar 27, which is mounted on and extends across the frame F in the same manner as core rods 28. Energization of coils carried in the

members

26,26 causes these members to move along

core rods

28,28 in a known manner. A stop element, for example, sleeve 29, is mounted on the guide rod 27 for limiting movement of the members 26. The stop element an be made adjustable, for example, by means of shims 30. A switch lug 81 is adjustably mounted on end plate 25a, for example, by means of adjusting screw 65. The screw 65 and switch lug 81 are positioned to engage switch actuators c and 850. Switch actuator 75(- controls contacts 75a and 75b of double pole double throw switch 75 and the switch actuator 82c controls

contacts

82a and 82b of double pole double throw switch 82 (FIG. 10). The limit switch actuators 75c and 820 control movement of the members 26 along the core rods 28 in a manner which will hereinafter be described in more detail.

Referring to FIG. 1, the drive system D is linked to the actuating mechanism A through a link 44, which is pivotally attached at one end to a bracket 45 on end plate 25, and which is pivotally connected at its other end, for instance, by means of a pin 43, to spring loading arm 21 of the actuating mechanism A. The spring loading arm 21 is mounted on operating shaft 41, which is rotatably mounted by means of bearings 46 to the side plates 47 of the actuating mechanism housing 108, as shown in FIG. 4. Thus it can be seen that movement of the

members

26,26 along

cores

28,28 causes the spring loading arm to move arcuately about the axis of operating shaft 41, for reasons will hereinafter be more fully described. In the preferred embodiment, and in embodiments employing a hand lever mounted on the end of shaft 41, the loading arm 21 is irrotatably fixed to the shaft 41, for example by slotting the arm 21 shown in FIG. 1. Arm 21 has not been shown as slotted in subsequent figures for purposes of clarity.

Referring to FIGS. 1 an 10, as heretofore noted, the operating lever 24 is rotatably mounted on the operating shaft 41. A tie bar is mounted at one end on the operating lever 24 and at the other end on stub arm 36. The stub arm 36 is also rotatably mounted-on the operating shaft 41. Thus the entire unit comprised of the stub arm 36, the tie bar 80, and the operating lever 24 is rotatably mounted with respect to the operating shaft 41. As shown in FIG. 10, the tie bar 80 has rotatably mounted therein a closing latch pin 79, which has a flat 94 formed thereon, and which carries an actuating arm 93. A biasing means, such as hair pin spring (shown in FIG. 6), biases the closing latch pin 79 so that the flat 94 is normally positioned as shown in FIG. 7. The tie bar 80 also includes a beveled face 103 in which is mounted a compression pin 102, the function of which will hereinafter be described.

Turning to FIGS. 3 and 4, the actuating system for opening and closing the switch SW includes closing ing means such as a trunnion 53 which is carried between the divider 58 and one of the side plates 47. One end of the member 50 is slidably received in the trunnion 53, and the opposite end of the member 50 carries a clevis 52, which is mounted on the end of the member 50. An energy-storing means. for example, a compression spring 51 or an aligned series of Belleville washers. is mounted on and surrounds the member 50. The

clevis 52 engages a clevis pin 92, which is mounted on the opening cam 23.

Similarly, a second longitudinally extending member 54 is slidably received in a trunnion 57 which is rotatably mounted in the housing 108. A clevis 56 is mounted on the other end of the member 54. An energy-storing means such as compression spring 55 is received on the member 54 and extends between the trunnion 57 and the clevis 56. The clevis 56 engages a clevis pin 37 on the closing cam 22.

Referring particularly to FIGS. 3, 4, and 7, a pawl 48 is rotatably mounted on the spring loading arm 21 by means of a pivot pin 49. The pawl 48 is positioned on the arm 21 by a resilient means such as hair pin spring 104 (FIG. 7). Disposed on the opposite end of pivot pin 49 is a flattened surface 61, which, shown in FIG. 3, is spaced closely adjacent an edge of opening cam 23. The pawl 48 includes a heel 76', which is positioned to engage a stop member, for example, stop screw 77, which is mounted on the divider 58.

The housing 108 also includes a stop member 60 positioned to engage the upper tip 59 of the closing cam 22. Also, the housing 108 includes a latch pin 71 rotatably mounted by means of bearings 72 between the side plates 47. The latch pin 71 holds the opening cam 23 in latched position will hereafter be described. The latch pin 71 also includes a flat surface 73.

A closing latch 62 (FIGS. 5 and 9) is freely rotatably mounted on the operating shaft 41. The latch 62 is joined to the closing cam 22 by a suitable fastener, for example, screw 63. The latch 62 includes a shoulder 64 which is positioned to be engaged by the latching surface 74 of the pawl 48.

Referring specifically to FIGS. 3 and 4, the switch actuating mechanism A includes a trigger system comprised of solenoid 83 which is disposed on the housing 108. The armature 96 of the solenoid is connected by suitable means to a pivotted link 84, which carries at one end a pin 84a. The pin 84a engages an actuating link 85. The link 85 carries a lug 86 which is pivotted to the link 85 by a pin 87. The lug 86 is fixed to latch pin 71 by a suitable fastener such screw 88. A compression spring 790 is disposed between the end of the link 85 adjacent the pivoted link 84 and the housing 108 to bias the link 85 to the position as shown in FIG. 3. A suitable detection circuit of types known in the art (not shown) for detecting ground faults, phase loss, blown fuses, etc., is utilized to energize solenoid 83. The triggering system can also be manually tripped by means of a push-button 95, which engages bell crank 97, mounted to the underside of the housing 108. A link 98 is pivotally mounted to the bell crank 97 at one end and is secured to the armature 96 of the solenoid 83.

FIG. 11 is a schematic diagram of a circuit for controlling the

induction motors

20,20. The lines 118, l 19, and 120 are three incoming power lines in a typical threephase power supply arrangement, which are connected to contacts of the switch SW. Three-phase power is drawn from the

incominglines

118, 119, and 120 through

lines

131, 132, and 133 to contacts 114, 115. 116, 123, 124, and 125 of a motor reversing switch MR. Power is supplied through the reversing switch to the

induction motors

20,20 through the

lines

134, 135, and 136. When

contacts

114, 115, and 116 are closed, power is supplied from

lines

131, 132, 133 to

lines

134, 135, and 136 in that order. When

contacts

123, 124, and 125 are closed, the

lines

131, 132, and 133 are connected to reverse order to

lines

136, 135, and 134 respectively. Power is also supplied to a stepdown transformer 110 through lines 137. The secondary of transformer 110 in turn powers a control circuit C for controlling the direction of travel of the

induction motors

20,20, as will hereinafter be described in more detail.

The preferred embodiment of the load break switch described above operates in the following manner. In FIGS. 3 and 4, the parts are shown in the positions assumed when the switch is open and ready to be actuated. The

springs

51 and 55 are extended and under comparatively light compression. Referring also to FIG. 11, the control circuit C is shown with the actuators 75c and 82c positioned in readiness for the closing of the switch. To load the actuating mechanism A, the manual push-buttom switch is momentarily closed and current is supplied through the normally open switch contacts 82a, which are closed by switch lug 81, and through normally closed contacts a to charge coil 111. Coil 111 is held in energized condition by a holding circuit including the contacts 112. When the coil 111 is energized, the

contacts

114, 115, and 116 of the reversing switch MR are closed while the contacts 123, 124, and remain open. In this manner, power is supplied through the

contacts

114, 115, and 116 and through

lines

134, 135, and 136 to the

induction motors

20,20. When so energized, the

members

26,26 of the

motors

20,20 begin moving, for example, toward the left side of the frame F, as shown in FIG. 3.

When the end plate 25a moves away from limit switch actuator 82, as shown in FIG. 1 switch contacts 82a open, but coil 111 remains energized through its holding circuit, including normally closed contacts 750 and contacts 112. In addition, normally closed contacts 821; are allowed to close, thereby arming a reversing circiut as will hereinafter appear.

As the

members

26,26 move, the link 44 rotates the spring loading arm 21 in a counter-clockwise direction about the axis of the operative shaft 41. As the arm 21 is moved arcuately, the flat portion 61 of the pivot pin 49 engages the edge of the opening cam 23, thereby driving the cam 23 in a counter-clockwise direction as illustrated in FIG. 5. The arcuate movement of the cam 23 causes the member 50 to slide through the trunnion 53, thereby compressing the spring 51. When the spring loading arm 21 has reached its limit of travel in the counter-clockwise direction, the opening cam 23 is latched in the position shown in FIG. 5 beneath the latching pin 71, which holds the cam 23 in this position, thereby holding spring 51 in a compressed, energystoring condition.

When the

members

26,26 reach the limit of travel in this first direction, the switch actuator 75c has been engaged by the head of the screw 65. When this occurs, the normally closed contact 75a is opened, thereby opening the holding circuit which previously held charge coil 111 energized. When the supply of current to coil 111 is terminated, the contacts 112 are opened and the supply of current to coil 111 is terminated, thereby opening

contacts

114, 115, and 1 16, thus terminating the supply of power to the

motors

20,20. Also, normally open contacts 75b are closed, and a circuit is established between closed contacts 75b and normally closed switch contact 82b to energize close coil 121. A suitable holding circuit including the switch 82b and contacts 122 holds the coil 121 energized When the coil 121 is energized, the

contacts

114, 115, and 116 remain open and the

contacts

123, 124, and 125 are closed. Therefore it can be seen that the power supplied to the

motors

20,20 in reversed phase from that previously described, and therefore, the

members

26,26 move in a reverse direction along the

cores

28,28.

Movement of the

members

26,26 in a reverse direction causes the spring loading arm 21 to move clockwise in an arc. Prior to this movement, however, the surface 74 of the pawl 48 will have engaged the shoulder 64 of the closing latch 62. It will be recalled that closing latch 62 is mounted on closing cam 22 so that rotation of the closing latch 62 causes the closing cam 22 to be rotated in a clockwise direction away from the stop 60. As the closing cam 22 is rotated in a clockwise direction, the clevis pin 37, acting through clevis 56, slides member 54 through trunnion 57, thereby compressing spring 55. It should be noted that as the cam 22 is rotated in a clockwise direction, its tip 78 rides past the flat surface 94 of the latch pin 79 carried by the tie bar 80, as clearly shown in FIG. 7A.

When the arm 21 reaches the position shown in FIG. 6, the heel 75 of the pawl 48 engages the stop screw 77. As the arm 21 continues to move, the bias of the spring 104 is overcome and the pawl 48 is rotated in a counter-clockwise direction, thereby causing the surface 74 to release its engagement with the shoulder 64 of the closing latch 62. When the cam 22 is thus released from engagement with the arm 21, the cam is driven in a counter-clockwise direction by the compressed spring -55 acting through clevis 56 and clevis pin 37. As this occurs, the tip 78 of the cam 22 engages latch pin 79 and drives the tie bar 80 and the operating arm 24 in a counter-clockwise arc to the position shown in FIG. 7, thereby causing arm 24, and associated linkage, to close the switch SW. The closing cam comes to rest with its upper tip 59 engaging the stop 60,-and the lower tip 78 engaging the latch pin 79 asshown in FIG. 7. Thus, at this point in the cycle, the switch SW is closed and the opening cam 23 is latched and holds springs 51 under compression.

When the

members

26,26 return to the position shown in FIG. 3, the contacts 82b are opened, thereby dropping out the holding circuit for coil 121, and causing

contacts

123, 124, and 125 to open and terminate the supply of power to the

motors

20,20. An auxiliary switch 126 is opened when the switch SW is closed, and closed when the switch SW is opened, so that the actuating mechanism cannot be initiated until the switch SW is open. Also, when the switch SW is closed, a limit switch 130 is also closed to arm the opening circuit containing the solenoid 83. The normally open contacts 129 are closed upon the detection of an appropriate signal from a detection circuit (not shown) which, when closed, causes power to be supplied to the solenoid 83.

The switch SW is caused to open in the following manner. In response to the generation of a signal from a suitable detecting circuit (not shown), for example, a ground fault detecting circuit, the solenoid 83 (FIG. 3) is energized, drawing armature 96 inwardly and causing lever 84 to pivot, thereby moving link 85. Movement of link 85 in turn causes lug 86 to rotate latch pin 71 to position the flat surface 73 to release the opening cam 23 from the latched position. When the cam 23 is unlatched, the spring 51, operating through the clevis 52 and the clevis pin 92, drives the opening cam 23 in a clockwise direction. The opening cam 23 engages the compression pin 102 and the surface 103 of the tie bar and drives the tie bar 80 and the operating lever 24 in a clockwise direction. As the clevis pin 92 moves, its head 91 engages arm 93, thereby causing the latch pin 79 to be rotated against the bias of spring to position the flat surface 94 as shown in FIG. 7A. This allows the latch pin 79 to clear the tip.78 of the closing cam 22. Thus it can be seen that the latch pin holds the switch SW in closed position until the opening cam is released. When the operating lever 24 is moved in a clockwise direction, the blades 33 of the switch SW are moved arcuately out of contact with tongues 35 by the linkage comprised of the pin 24a, the swivel joint 32, and the crossbar 31. The purpose of the compression pin 102 is to absorb a portion of the impact of the cam 23 against the surface 103 to cushion the parts of the apparatus from undue shock. The compression pin 102 also acts as a means to eliminate the recoil of the switch actuating mechanism when the switch SW arrives at its fully open position.

Referring to FIGS. 3 and 4, the switch SW can also be opened manually by means of a push-button 95. The pushbutton engages a bell crank 97. One end of a link 98 is pivotally connected to the bell crank 97 and at the other end is attached to the armature 96 of the solenoid 83, as for example, by nut 99. Movement of the pushbutton inwardly moves the armature 96 in the same direction as if the coil of the solenoid 83 was energized, thereby unlatching the opening cam 22 in the manner heretofore described.

Referring to FIG. 1, the housing 108 includes a trim plate 106a. A safety switch 107 and fuse access door are held in closed position by the plate 106a. When the plate is removed, the switch 107 is opened, thereby disabling control circuit C (FIG. 1 1), so that the drive system D cannot be actuated when maintenance is being performed on the switch. The switch 70 may be mounted on the housing 108 as shown, or at a location remote from the switch.

Overload relays 128 are provided in the control circuit C and in

lines

134 and 136 to protect the control circuit and the

motors

20,20 from burn-out in the event that excessive current is supplied to the motors.

It can readily be seen that the switch as disclosed above yields many advantages. Reliability of the switch is enhanced by reason of the relative simplicity of the actuating mechanism, by the use of two independent energy-storing members, one for opening, and the other for closing the switch, and also by reason of the fact that the switch cannot be closed until after the energy-storing member for opening the switch has been charged and latched.

In addition, the drive system is used only to load the energy-storing members, and not to open or close the switch contacts. Thus the switch is capable of opening under conditions of reduced voltage, thereby fulfilling required performance specifications. In addition, the design lends itself to either manual or power actuation.

' Also, the switch is compact, yet easy to maintain. Further, projecting handles or levers which can cause injury to bystanders when the switch is unexpectedly opened, can be eliminated.

As numerous changes may be made in the above described construction, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted illustrative, and not in a limiting sense. When used in the claims hcreinafter, the term linear actuator means a motor having a driven element to which is imparted translational motion in a linear or non-linear path rela tive to a fixed element of the motor.

We claim:

1. An actuating mechanism for a load break switch having contacts movable into and out of engagement comprising a frame, a loading'member, means pivotally mounting the loading member on the frame, an opening cam rotatably mounted on the frame, a first energystoring member for storing energy in response to movement of the opening cam in a first direction, means coactive between the opening cam and the loading member for moving the opening cam in said first direction in response to movement of the loading member in a first direction, latch means for holding the first energystoring member in an energy-storing condition, a cl'osing cam rotatably mounted on the frame, a second energy-storing member in engagement with the closing cam, releasable latch means coactive between the loading member and the closing cam for moving the closing cam in a first direction in response to movement of the loading member in a second direction, a switchoperating means rotatably mounted on the frame for opening and closing the contacts of the switch, release means for releasing the releasable latch means after the closing cam has actuated the second energy-storing member to store energy therein, means carried by the switch operating means for engaging the closing cam as it is driven by the second energy-storing member means for releasing the first-mentioned latch means, and means carried by the operating means for engaging the opening cam as it is driven by the first energy-storing member.

2. An actuating system in accordance with claim 1 wherein the first and second energy-storing members are springs.

3. An actuating mechanism in accordance with claim 1 which further comprises a motor means for driving the loading member in the first and second directions.

4. An actuating mechanism in accordance with claim 3 wherein the motor means is an induction motor having a stationary core and a member movable along the core.

5. An actuating mechanism for a load break switch having a switch element movable between opened and closed positions comprising, a shaft, a switch operating means for opening and closing the switch element rotatably mounted on the shaft, a loading member mounted for arcuate movement about the longitudinal axis of the shaft, an opening cam freely rotatably mounted on the shaft, a first energy-storing means in engagement with the opening cam, a closing cam freely rotatably mounted on the shaft, a second energystoring means in engagement with the closing cam, means responsive to movement of the loading means in a first direction for rotating the opening cam and thereby loading the first energy-storing means, means responsive to movement of the loading means in a second direction to rotate the closing cam, thereby to load the second energy-storing means, latch means for engaging the opening cam to hold the first energy-storing means in energy-storing condition, means responsive to continued movement of the loading means in the second direction for releasing the loading means from driving engagement with the closing cam to allow the closing cam to be driven by the second energy-storing means in a direction opposite from that in which it was driven by the loading means, trigger means for releasing the latch means to allow the opening cam to be driven by the first energy-storing means, means mounted on the switch operating means for engaging the opening cam and the closing cam whereby the opening cam and the closing cam rotate the operating means to switch opening and switch closing positions respectively, and drive means for driving the loading means.

6. An actuating mechanism in accordance with claim 5 wherein the drive means comprises a linear induction motor and control means for causing the motor to move in a first direction, and in a second direction reverse from the first direction.

7. An actuating mechanism in accordance with claim 5 wherein the energy-storing members comprise springs and means to place the springs in energy-storin g condition.

8. The actuating mechanism in accordance with claim 5 wherein the first energy-storing means when released drives the opening cam in one direction, and the second energy-storing means when released drives the closing cam in an opposite direction.

9. An actuating mechanism in accordance with claim 5 wherein the engagement means carried by the operating means includes a latch element for engaging the switch opening cam when the operating means is in a switch closing position, and means responsive to movement of the first energy-storing means for releasing said latch means.

10. The actuating mechanism in accordance with claim 5 wherein the means for driving the closing cam comprises a rotatable pawl carried by the loading member, and means carried by the closing cam for engaging the pawl.

11. An actuating mechanism in accordance with claim 5 wherein the engagement means further includes means for cushioning the impact of the opening cam on the engagement means.

12. A load break switch comprising a switch element, an actuating mechanism for opening and closing the switch element, including first and second energystoring means for opening and closing the switch element, loading means movable in first and second directions, means responsive to movement of the loading means in a first direction for loading one of the energystoring means, means responsive to movement of the loading means in a second direction for loading the other of the energy-storing means, and drive means for driving the loading means, the drive means comprising a linear induction motor.

13. A switch as in claim 12 and further comprising control means for controlling the induction motor including a first switch means engageable by the motor causing the motor to move in the first direction, and a second switch means for causing the motor to move in the second direction.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 911 240 DATED December 5, 1975 INV ENTOR(S) Louis S. Henderson 5 Gustav E. Lachman It is certified thaterror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 1, change "an to --can-. Column 4, line 21, insert -shaft-- after "which". Column 4, line 33, change "an" to -and-. Column 6, line 2, "t first occurrence to in Column 6, line 18, change "buttom" to -button--. Column 7, line 26, change "75" to --76-.

Signed and Scaled this second Day of March 1976 [SEAL] A ttes t:

RUTH C. MASON Commissioner ofParents and Trademarks UNITED sTATEs PATENT AND TRADEMARK OFFI-CE CERTIFICATE OF CORRECTION PATENT NO. 3 911 240 DATED December 5, 1975 INVENTOR(S) Louis S Henderson (5 Gustav E. Lachman It is certified thaterror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 1, change "an to can Column 4, line 21, insert --shaft after "which". Column 4, line 33, change "an" to and. Column 6, line 2, first occurrence to in Column 6, line 18, change "buttom" to --button. Column 7, line 26, change "75" to 76.

signed and Sealed this second Day Of March 1976 [SEAL] Attest:

RUTH c. MASON c. MARSHALL DANN Arresting Officer (ommisxivner of Parents and Trademarks

Claims

1. An actuating mechanism for a load break switch having contacts movable into and out of engagement comprising a frame, a loading member, means pivotally mounting the loading member on the frame, an opening cam rotatably mounted on the frame, a first energy-storing member for storing energy in response to movement of the opening cam in a first direction, means coactive between the opening cam and the loading member for moving the opening cam in said first direction in response to movement of the loading member in a first direction, latch means for holding the first energy-storing member in an energy-storing condition, a closing cam rotatably mounted on the frame, a second energy-storing member in engagement with the closing cam, releasable latch means coactive between the loading member and the closing cam for moving the closing cam in a first direction in response to movement of the loading member in a second direction, a switchoperating means rotatably mounted on the frame for opening and closing the contacts of the switch, release means for releasing the releasable latch means after the closing cam has actuated the second energy-storing member to store energy therein, means carried by the switch operating means for engaging the closing cam as it is driven by the second energy-storing member means for releasing the first-mentioned latch means, and means carried by the operating means for engaging the opening cam as it is driven by the first energy-storing member.

5. An actuating mechanism for a load break switch having a switch element movable between opened and closed positions comprising, a shaft, a switch operating means for opening and closing the switch element rotatably mounted on the shaft, a loading member mounted for arcuate movement about the longitudinal axis of the shaft, an opening cam freely rotatably mounted on the shaft, a first energy-storing means in engagement with the opening cam, a closing cam freely rotatably mounted on the shaft, a second energy-storing means in engagement with the closing cam, means responsive to movement of the loading means in a first direction for rotating the opening cam and thereby loading the first energy-storing means, means responsive to movement of the loading means in a second direction to rotate the closing cam, thereby to load the second energy-storing means, latch means for engaging the opening cam to hold the first energy-storing means in energy-storing condition, means responsive to continued movement of the loading means in the second direction for releasing the loading means from driving engagement with the closing cam to allow the closing cam to be driven by the second energy-storing means in a direction opposite from that in which it was driven by the loading means, trigger means for releasing the latch means to allow the opening cam to be driven by the first energy-storing means, means mounted on the switch operating means for engaging the opening cam and the closing cam whereby the opening cam and the closing cam rotate the operating means to switch opening and switch closing positions respectively, and drive means for driving the loading means.

7. An actuating mechanism in accordance with claim 5 wherein the energy-storing members comprise springs and means to place the springs in energy-storing condition.

12. A load break switch comprising a switch element, an actuating mechanism for opening and closing the switch element, including first and second energy-storing means for opening and closing the switch element, loading means movable in first and second directions, means responsive to movement of the loading means in a first direction for loading one of the energy-storing means, means responsive to movement of the loading means in a second direction for loading the other of the energy-storing means, and drive means for driving the loading means, the drive means comprising a linear induction motor.